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Three-phase Commit Protocol
In computer networking and distributed databases, the three-phase commit protocol (3PC) is a distributed algorithm that ensures all nodes in a system agree to commit or abort a transaction. It improves upon the two-phase commit protocol (2PC) by eliminating the possibility of indefinite blocking caused by a specific type of failure during the commit phase. Motivation A two-phase commit protocol cannot dependably recover from a failure of both the coordinator and a cohort member during the Commit phase. If only the coordinator had failed, and no cohort members had received a commit message, it could safely be inferred that no commit had happened. If, however, both the coordinator and a cohort member failed, it is possible that the failed cohort member was the first to be notified, and had actually done the commit. Even if a new coordinator is selected, it cannot confidently proceed with the operation until it has received an agreement from all cohort members, and hence must bloc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Networking
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or by wireless communication. The devices may be connected in a variety of network topologies. In order to communicate over the network, computers use agreed-on rules, called communication protocols, over whatever medium is used. The computer network can include personal computers, Server (computing), servers, networking hardware, or other specialized or general-purpose Host (network), hosts. They are identified by network addresses and may have hostnames. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database
In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an application associated with the database. Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed Algorithm
A distributed algorithm is an algorithm designed to run on computer hardware constructed from interconnected processors. Distributed algorithms are used in different application areas of distributed computing, such as telecommunications, scientific computing, distributed information processing, and real-time process control. Standard problems solved by distributed algorithms include leader election, consensus, distributed search, spanning tree generation, mutual exclusion, and resource allocation. Distributed algorithms are a sub-type of parallel algorithm, typically executed concurrently, with separate parts of the algorithm being run simultaneously on independent processors, and having limited information about what the other parts of the algorithm are doing. One of the major challenges in developing and implementing distributed algorithms is successfully coordinating the behavior of the independent parts of the algorithm in the face of processor failures and unreliable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed System
Distributed computing is a field of computer science that studies distributed systems, defined as computer systems whose inter-communicating components are located on different networked computers. The components of a distributed system communicate and coordinate their actions by passing messages to one another in order to achieve a common goal. Three significant challenges of distributed systems are: maintaining concurrency of components, overcoming the lack of a global clock, and managing the independent failure of components. When a component of one system fails, the entire system does not fail. Examples of distributed systems vary from SOA-based systems to microservices to massively multiplayer online games to peer-to-peer applications. Distributed systems cost significantly more than monolithic architectures, primarily due to increased needs for additional hardware, servers, gateways, firewalls, new subnets, proxies, and so on. Also, distributed systems are prone to fa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commit (data Management)
In computer science and data management, a commit is a behavior that marks the end of a transaction and provides Atomicity (database systems), Atomicity, Consistency (database systems), Consistency, Isolation (database systems), Isolation, and Durability (database systems), Durability (ACID) in transactions. The submission records are stored in the submission Log file, log for recovery and consistency in case of failure. In terms of transactions, the opposite of committing is giving up tentative changes to the transaction, which is rolled back. Due to the rise of distributed computing and the need to ensure data consistency across multiple systems, commit protocols have been evolving since their emergence in the 1970s. The main developments include the Two-phase commit protocol, Two-Phase Commit (2PC) first proposed by Jim Gray (computer scientist), Jim Gray, which is the fundamental core of distributed transaction management. Subsequently, the Three-phase commit protocol, Three- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Database Transaction
A database transaction symbolizes a unit of work, performed within a database management system (or similar system) against a database, that is treated in a coherent and reliable way independent of other transactions. A transaction generally represents any change in a database. Transactions in a database environment have two main purposes: # To provide reliable units of work that allow correct recovery from failures and keep a database consistent even in cases of system failure. For example: when execution prematurely and unexpectedly stops (completely or partially) in which case many operations upon a database remain uncompleted, with unclear status. # To provide isolation between programs accessing a database concurrently. If this isolation is not provided, the programs' outcomes are possibly erroneous. In a database management system, a transaction is a single unit of logic or work, sometimes made up of multiple operations. Any logical calculation done in a consistent mode in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-phase Commit Protocol
In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC, ''tupac'') is a type of Atomic commit, atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that participate in a Distributed transaction, distributed atomic transaction on whether to Commit (data management), commit or abort (roll back) the transaction. This protocol (a specialised type of Consensus (computer science), consensus protocol) achieves its goal even in many cases of temporary system failure (involving either process, network node, communication, etc. failures), and is thus widely used.Phil Bernstein, Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (1987) ''Concurrency Control and Recovery in Database Systems'' Chapter 7, Addison Wesley Publishing Company, Gerhard Weikum, Gottfried Vossen (2001) ''Transactional Information Systems'' Chapter 19, Elsevier, Philip A. Bernstein, Eric Newcomer (2009)''Principles of Transact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-phase Commit Protocol
In transaction processing, databases, and computer networking, the two-phase commit protocol (2PC, ''tupac'') is a type of Atomic commit, atomic commitment protocol (ACP). It is a distributed algorithm that coordinates all the processes that participate in a Distributed transaction, distributed atomic transaction on whether to Commit (data management), commit or abort (roll back) the transaction. This protocol (a specialised type of Consensus (computer science), consensus protocol) achieves its goal even in many cases of temporary system failure (involving either process, network node, communication, etc. failures), and is thus widely used.Phil Bernstein, Philip A. Bernstein, Vassos Hadzilacos, Nathan Goodman (1987) ''Concurrency Control and Recovery in Database Systems'' Chapter 7, Addison Wesley Publishing Company, Gerhard Weikum, Gottfried Vossen (2001) ''Transactional Information Systems'' Chapter 19, Elsevier, Philip A. Bernstein, Eric Newcomer (2009)''Principles of Transact ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paxos Algorithm
Paxos is a family of protocols for solving Consensus (computer science), consensus in a network of unreliable or fallible processors. Consensus is the process of agreeing on one result among a group of participants. This problem becomes difficult when the participants or their communications may experience failures. Consensus protocols are the basis for the state machine replication approach to distributed computing, as suggested by Leslie Lamport and surveyed by Fred B. Schneider, Fred Schneider. State machine replication is a technique for converting an algorithm into a fault-tolerant, distributed implementation. Ad-hoc techniques may leave important cases of failures unresolved. The principled approach proposed by Lamport et al. ensures all cases are handled safely. The Paxos protocol was first submitted in 1989 and named after a fictional legislative consensus system used on the Paxi, Paxos island in Greece, where Lamport wrote that the parliament had to function "even thou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
